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Humidifier for two-pipe steam house with attic A/C?

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jefff
jefff Member Posts: 4
in Strictly Steam
I have a Hoffman vapor vacuum two-pipe steam system with traditional radiators. The heating is actually running quite well in part thanks to these forums and the info gained from them. I have air conditioning in the unconditioned attic (insulated flexible ducting) with a majority of the balance going to the warmer-in-summer second floor.

I'd like to find a way to add on whole-house humidification as the dry air and static create some nuisance-level comfort issues.

Is it possible, or wise, or widely recommended to add a furnace-plenum style humidifier to an attic A/C system? The unit does have a drain pan and drain pump for AC condensation.

I know the larger picture solution would have me doing a lot more draft-stopping and air tightness to keep the cold dry air outside where it belongs. But am I missing a better/easier solution for the time being?

Thanks!

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  • ChrisJ
    ChrisJ Member Posts: 15,673
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    I've been tempted to try this as I installed a system in my attic 2 years ago.

    But my concern is getting condensation in the cool ductwork which is up in the attic.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • jefff
    jefff Member Posts: 4
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    Condensation in the ductwork is a concern, yes. Also, furnace humidifiers have quite hot air in the range of 150F passing through them that would help in the evaporation and humidity carrying capacity. I'm not sure that a humidifier sized for a furnace in a particular house would have adequate output if placed in the 70F ambient "return" air in an attic AC.
  • mikeg2015
    mikeg2015 Member Posts: 1,194
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    Steam humidifier will work, but you’ll need a fair amount of airflow to prevent condensing. I’d getting away with 500CFM on a Aprilaire running at 240V, I think 5KW. Warning, if your envelope is leaky, it’s a pretty good energy hog. But I’ve been able ot humidify a 3500sqft Victorian using just the downstairs system since in winter heat and humidity rises due to stack effect.
  • SuperTech
    SuperTech Member Posts: 2,160
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    An Aprilaire 800 can be installed inside of a closet and the steam pipe run up to the attic to the plenum. This way no water supply pipes or condensate drains are in an unconditioned area and exposed to freezing temperatures. I have installed a few of them like this with no issues. The 800 is a great unit and requires that the steam canister is replaced annually.

    Whatever you do please stay away from the Honeywell true steam humidifier, if they still make that awful piece of junk.
  • John Mills_5
    John Mills_5 Member Posts: 951
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    I think the True Steam has been put out to pasture. Good riddance. The 800 doesn't even need to run to the air handler. Can be run to a termination in the conditioned space like 1st floor if the hum is mounted in the basement.
    SuperTech
  • mikeg2015
    mikeg2015 Member Posts: 1,194
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    SuperTech said:

    An Aprilaire 800 can be installed inside of a closet and the steam pipe run up to the attic to the plenum. This way no water supply pipes or condensate drains are in an unconditioned area and exposed to freezing temperatures. I have installed a few of them like this with no issues. The 800 is a great unit and requires that the steam canister is replaced annually.



    Whatever you do please stay away from the Honeywell true steam humidifier, if they still make that awful piece of junk.

    True steam I think uses regular resistance units and requires major cleaning at least annually with descalers. The Aprilaire method is great. About once a season you just replace the canister. Takes about 5 minutes. No mess.

    Only think about steam is the electric bill. Humidity isn’t free. Budget money for air sealing, especially on the upper floors.
    SuperTech
  • Steamhead
    Steamhead Member Posts: 16,835
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    How about some of these?

    https://heatinghelp.com/store/detail/hvac-plastic-hang-on-steam-radiator-humidifier
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    SuperTech

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